Implement dream out overlay transition

The overlay should blur and animate the complications when the dream is waking up. This adds a new API to DreamOverlayService to get notified of dreams waking, so that it can run the animation. When the animation is done, we communicate back to the DreamService so that it may finish itself.

A delay was added to the touch handler which hides the overlay when a
touch happens, in order to ensure the exit animation has a chance to
complete first.

Bug: 220311554
Test: atest DreamOverlayAnimationsControllerTest
Test: atest HideComplicationTouchHandlerTest
Test: atest DreamOverlayContainerViewControllerTest
Test: atest DreamOverlayServiceTest
Test: flashed device and verified animation looks correct when tapping
dream to exit

Change-Id: Ibccd45aefbf9b8aeb462d843794c3434c49a6bf2